The first "real" instrument that I'm going to build is the autopilot module.

When it will be completed (I already know it will take a pretty long time) and together with the glass cockpit (running on a networked PC) I will be able to make a flight without the need to use the mouse (and the keyboard) to set up all the autopilot functions.


As you can see from the picture above, it is composed by 3 displays: two for the NAV freq. and one for the various settings (altitude, IAS, HDG etc).

I decided to start from the NAV displays where the choice of the components is between classic 7-segment displays or alphanumeric LCD displays.

I've chosen the second option using a 8x2 LCD alphanumeric

display equipped with the Hitachi HD44780.

A word about the HD44780 (you can find its datasheet here


It's a simple display module that needs just a few external signals to be able to display something on the screen.

You can also set up till 8 user defined characters to customize your text.

I found two of them on EBAY for about 10 Euro (shipping charge included !!).

After spending some hour to study the datasheet, I decided to connect it to the parallel port of my pc, driving all the signals through a simple interface following this wiring

scheme: (I modified the scheme found on the forum of


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